Some power transmission devices applied to a traveling system of an industrial vehicle such as a wheel loader decelerate rotation of an axle shaft by a deceleration mechanism and then transmit the rotation to a wheel hub. This kind of power transmission device is provided with a wet type multiple-disc brake mechanism between a spindle case and a wheel hub provided around the axle shaft and power transmission devices configured to apply braking on the wheel hub by actuation of the brake mechanism are provided (for example, see Patent Literature 1).
However, the power transmission device of Patent Literature 1 has a configuration in which the brake mechanism is provided around the outer circumference of the wheel hub, so that there is a problem that it is difficult to reduce the size of the brake mechanism. Therefore, conventionally, power transmission devices in which the brake mechanism is provided between the axle shaft and the spindle case are provided. According to this power transmission device, the brake mechanism may be provided around the outer circumference of the axle shaft, so that it is possible to reduce the size of the brake mechanism (for example, see Patent Literature 2).